1. Field of the Invention
This invention relates to a method of enhancing the rate of growth of aquatic life such as fish, mollusks and crustacea, and in particular to fish farming in which fish are grown in water which is artifically oxygenated.
An object of the invention is to increase the growth rate of fish, particularly trout, in commercial fish farms.
2. Prior Art
It is known to bubble air through the water of rivers, reservoirs, lagoons and aquaria in order to raise the level of dissolved oxygen therein.
In an article published in "Aquaculture" (April 1972) it is stated on page 323 that the optimum conditions for rearing salmonids occurs when air is bubbled through the water to maintain the dissolved oxygen level in the water between 80% and 100% saturation. The same article also states that it is undesirable to aerate the water so that the dissolved oxygen in the water exceeds 105%.
Fish farming or fish husbandry systems as they are sometimes called, are disclosed in U.S. Pat. Nos. 3,643,403, 3,756,197 and 3,996,893. The prior art patents disclose utilizing oxygen or an oxygen containing gas (e.g. air) injected into a confined body of water to raise fish.
U.S. Pat. No. 3,756,197 discloses using a hood to saturate the water under the hood with oxygen whereby the oxygen level under the hood could be in excess of 200%. However, U.S. Pat. No. 3,756,197 does not disclose maintaining the entire fish farming water at a level above saturation with respect to ambient air.